Lifting jack



06?. 11, 1932. HOBBS 1,882,598

LIFTING JACK Filed March 28, 1928 2 Sheets-Sheet 1 Ja% Mzfos J. w. HOBBS LIFTING JACK Filed March 28, 1928 2 Sheets-Sheet 2 Patented Oct. 11, 1932 UNITED STATES:

PATENT OFFICE 2 JOHN W; HOBBS, OE MOLINE, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS,'TO THE DUFF-NORTON- MANUFACTURING COMPANY, OF PITTSBURGH, PENNSYLVANIA, A

conronnrion or PENNSYLVANIA rrrrrns moi: 7

Application filed March 38, 1928. Serial No. 265,291.

My invention relates to lifting jacks whose rams or lifting members are pneumatically controlled. 1 y

My invention hasi'or its. object the pro vision of mechanism for relieving such a ram of its operating influence .up-onreaching a predetermined position with respect to its jack frame. In carrying out my invention, I employ an air operated ram operating motor,

valve mechanism controlling the flow of com pressed air through the motor, and mecha nism governing the valve mechanism and governed by the ramof the corresponding jack in a manner to cut off the flow of air to the motor when the ram reaches each end of its travel. I i

The invention will be more fully explained in connection with the accompanying drawings in which Fig. 1 is a View, partially in sectional elevation'and partially in full ielevation of the preferred embodiment of'the invention; Fig. 2' is a-sectional viewon line Y 2-2 of Fig. 1; Fig. 3 is a sectional view on line 33 of Fig. 1 ,Fig. 4 is a View diagrammatically illustrating the invention, the portions appearing in full lines showing the condition which obtains when the'ram is to be lifted from its lowermost positiointhe portions illustrated by the dot and dash lines showing the condition which obtains when the ranrlias'reached its uppermost position,

the ram has reached its lowermostposition,.

the air motor then being stopped; and Fig. 6 is a sectional view on line 6- 6 of Fig. l.

A jack frame 1 may be of any usual or preferred construction. thisframe terminat ing in anupper sleevevor cylinder portion Q 2 which is vertically arranged and serves as a guide for the ram 3 which is movable longitudinally or along its axis, that is, lineally. The ram 3 terminates in a load sustaining head a which is shown as being in the nature. of a flange on the upper end of the ram and which contacts with or is in close proximity to the upper end of the sleeve 2 when the ram is in its lowermost position.

The ram is hollow and interiorlv threaded to receive a jack screw '5 in threaded engageby a thrust bearing structure which is inclusive of balls or:rollers '7. The ram is raised and lowered byemeans of an air operated mtor8 of any preferred constructionfthis motor serving to d'rive the spurpinion 9 which is in mesh with a spur gear 10. A bevel pinion 11 is, fixed With respect to and is coaxial with the spur gear, the bevel pinion being in mesh with the bevel gear 6. lVhen the'air operated motor is being driren by compressed air, it serves to turn the jack screw through the intermediation of the gearing which has been described to raiseor lower the ram. V

The compressed air for operating the air motor is suppliedto the motor from a suitable source of air under pressure'and through the piping. 12 which discharges into the annular passage 13 formed in a casing 14. The airflows from the passage through the radially aligned ports 15 in the hollow lug 16, said ports communicating with the ore 17 of said plug. Said bore discharges into hebore 18 of a hollow valve stem section 19, the bore 1 8, in turn, discharging through the port 20 in the valve stem section 19 and into the'fcylindrical clearance which intervenes between said valve stem section and the stationary upright sleeve 21 into whose upper end the plug 16 is screwed and which is clamped at its lower end in assembly with the tubular continuation 22 of the casin of the air motor by means of a nut 23.' aid nut has an internal shoulder 24 which surroundsthe sleeve 21 and is clamped dowm wardly upon the flange 25 of the sleeve, this flange being consequently clamped down upon the upper end 'ofthe tubular continuation 22 of the motor casing. A valve 26 (Figs. 4 and 5) is coupled with the hollow valve stem section 19 by'the solid valve stem section 27,. the clearance between the stem passes into the channel 29 that discharges into the valve casing 28. Channels 30 and 31 radiate from the valvecasing which discharges into the one or the other of these latter two channels or into neither of them, accordingto the position of the valve. When the valve is in the position shown b full lines in Fig. 4, the motor is operated in the direction in which the ram 3 will be lifted, and when the valve is in the position shown by dotted lines in this figure, the motor is stopped, both channels 30 and 31 being then closed by the valve. When the valve is'in the position shown by full lines in Fi 5 the motor is operated in the direction in which f 3' the ram 3 will be lowered, and when the valve is in the position shown bv dotted lines in this figure, the motor is stopped, both channels and 31 again being closed by the valve. r V

The valve isturned by means of a lever 32 whose hub is journaled upon the sleeve 21 and which hub carries a pin 33 that passes through an elongated horizontal arcuate slot in said sleeve, this pin being screwed into the valve stem section 19, whereby the stem moves in company with the lever to operate the valve. I portion 34 by which it is to be moved to effect either of the valve opening adjustments shown in Figs. 4 and 5 to effect the elevation and depression of the ram, respectively. The lever is automatically operated to occupy the position shown by dot and dash lines in Fig. 4 to close the valve when the ram has been brought to its uppermost position and is automatically operated to occupy the position shown by dot and dash lines in Fig. 5 to close the valve when the ram has been brought to its lowermost position. The mechanism which is employed for automatically closing the valve is such as to permit the valve to be closed by hand when the ram is between its upper andlower limiting positions, and to permit it to be openedto operate the motor in the proper direction only when the ram is in either. of its extreme positions. 'The mechanism illustrated for effecting the automatic closure of the valve and that permits such manual operation of the valve is inclusive of a rocker arm 35, intermediately pivoted at 36 upon the housing bracket 37 which is provided upon the jack frame sleeve 2. This lever has a wing extension 38 which has an arcuate slot 39 therethrough, the long sides of 5 this slot having their centers substantially in The lever is formed with a handlethe axis of turning movement of said rocker arm. A link 40 is connected at one end with an ear 41 which projects laterally from the lever 32, this end of the link being bent to pass through said ear. The other end of the link is also bent and passes through the aforesaid arcuate slot. Cotter pins may be employed to hold the ends of the link in assembly with the parts through which they pass. Theend of the link which is received in said arcuate slot is adapted to travel in said slot from end to end thereof, the link thus being.

sure of the valve when the ram has reached either limit of its travel to avoid injury. As illustrated in Fig. 1, and by full lines in Fig. 4, the valve has just been manually opened to effect the elevation of the ram of the jack. W'henthe ram reaches the upper limit of its travel, the rocker arm 35 is automatically turned counterclockwise to .bring the valve to its closed position to'stop further elevation of the ram, the right hand end of the link 40 being then in engagement with the left hand end of the arcuate slot 39. This counterclockwise movement of the rocker arm occurs when the dog 42 is received within the annular groove or recess 43 formed in the ram near its lower end and is brought to the level of the nose of the dog when the ram has been raised to its upper limiting position.

As illustrated by full lines in Fig. 5, the valve has just been manually opened to effect the lowering of the ram of the ack. When the rain reaches the lower limit of its travel, the rocker arm 35 is automatically turned clockwise to bring the valveto its closed position to stop further lowering of the ram, the right hand end of the link 40 being then in engagement with the right hand end of the arcuate slot 39. This clockwise movement of the rocker arm occurs when the dog 44 is received within the annular groove or recess 45 formed in the ram and near its upper end and is brought to the level of the nose of the dog when the ram has been lowered to its lower limiting position.

Coiled springs or spring cushions 46 and 47 intervene betweenthe ends of the rocker arm and the dogs 42 and 44, respectively. These springs operate to press the dogs 42 and 44 against the side of the plunger. When the ram approaches the downward limit of its travel, the dog 44 drops into the recess 45 and slight further downward movement of the ram acts to move the rocker in the clockwise direction, the dog then serving as a thrust connection. Similarly when the'ram approaches the upper limit, the tip of dog 42 drops into recess 43 and slight continued upward movement of the ram acts through this dog as a thrust element to move the rocker in the counter-clockwise direction.

Changes may be made without departing from the invention.

I ting 01f flow of operating air to said motor;

a rocker arm connected with said'valve to close 1t; a dog upon the rocker arm; and spring means pressing said dog upon said member, the member having a recess which is positioned to receive the nose of said dog when the member has been brought to a predetermined position whereby the member acts through said dog to turn the rocker arm to 1 opened independently thereof; a dog upon the rocker arm; and spring means pressing said dog upon said member, the member having a recess which is positioned to receive the nose of said dog when the member has been brought to a predetermined position whereby the member acts through said dog to turn the rocker arm to close the valve. h

3. In a lifting .jack, the combination with a vertically movable jack member, of an air operated motor in operating relation to said member; a valve for establishing and cutting off flow of operating air to said motor; a rocker arm connected with said valve to close it; two dogs upon the rocker arm; and spring means pressing said dogs upon said member, the member having a recess which is positioned to receive the nose of one of said dogs when the member has been brought to a predetermined position whereby the member acts through said dog to turn the rocker arm to close the valve, said member having another recess which is positioned to receive the nose of the other dog when the member has been moved in a reverse direction to another predetermined position whereby the member acts throughthis dog to turn the rocker arm to again close the valve.

4:. In a lifting jack, the combination with a vertically movable jack member, of an air operated motor in operating relationto said Having thus described my invention, I

member; a valve for establishing and cutting off flow ofoperating air to said motor; a

rocker arm in lost motion connection with said valve 'to' close it and to permit it to be opened independently thereof; two dogs upon the rocker arm; and spring means pressing saiddogs upon said member, the

member having a recess which is positioned to. receive the nose of one of said dogs when the member has been brought to a predetermined position whereby the member acts through said dog to turn the rocker arm to closethe valve, said member having another:

recess which ispositioned to receive the nose of the other dog when the member has been moved in a reverse direction to another predetermined position whereby the member acts through this dog to turn the rocker arm to again close the valve.

5.1In a lifting jack, the combination with the ram thereof; of a jack screw in threaded connection with the ram; an air operated motor in turning relation to said ack screw for mo'ving'the ram; a valve for establishing and cutting off flow of operating air to said motor; a rocker arm connected with said valve to close it; a dog upon the rocker arm; and spring means pressing said dog upon said ram, the ram having a recess which is positioned to receive the nose of said dog when the ram has been brought to a predetermined position whereby the ram acts'through said dog to turn the rocker arm to close the valve. i

6. In a lifting ack, the combination with the ram thereof; of a'jack screw in threaded connection with the ram; an air operated motor in turning relation to said jack screw for moving the ram; a valve for establishing and cuttingvoii flow of operating air to said motor; a rocker arm in lost motion con-- nection with said valve to close it and to permit it to be opened independently thereof; a dog upon the rocker arm; and spring means pressing said dog upon said ram, the member having a recess which ispositioned to receive the nose of said dog when the ram has been brought to a predetermined position whereby the ram acts through said dog to turnthe rocker arm to close the valve.

7. In a lifting jack, the combination with the ram thereof; of a jack screw in threaded connection with the ram; an air operated motor in turning relationto said jack screw for moving the ram; a valve for establish ing. and cutting off flow of operating air to said motor; a rocker arm connected with said valve to close it; two dogs upon the rocker arm; and spring means pressing said dogs upon said ram, the ram having a recess which is positioned to receive the nose of one of said dogs when the ram has been'brought to a predetermined position whereby the ram acts through said dog to turn the rocker arm to close the valve, said ram having another recess which is positioned to receive the nose of the other dog when the ram has been moved in a reverse direction to another predetermined position whereby the ram acts through this dog to turn the rocker arm to again close the valve. 7

8. In a lifting jack, the combination with the ram thereof; of a jack screw in threaded connection with the ram; an air operated motor in turning relation to said ackscrew for moving the ram; a valve for establishing and cutting on he v of operating air to said motor; a rocker armin lost motion connection with said valve toclose it and to permit it to be opened independently thereof; two

dogs upon the rocker arm; and spring means pressing said dogs upon said ram, the ram having a recess which is positioned to receive the nose of one of said dogs when the ram has been brought to a predetermined position whereby the ram acts through said-dog to turn the rocker arm to close the valve, said ram having another recess which is positioned to receive the nose of the other dog when the ram has been moved in a reverse direction to another predetermined position whereby the ram acts through this dog to turn the rocker arm to again close the valve.

.9. In a lifting jack, the combination of a standard, a lifting ram guided in the standard, a lifting screw coacting with said ram, an air-operated motor geared to the lifting. screw, a valve for establishing and cutting off flow of operating air to said motor, manual means for operating said valve to start the motor in either direction and to stop it, and means for automatically shifting said valve to stop position when the ram reaches both upper and lower predetermined limits of motion, said means comprising elements on the upper and the lower portions of the ram, and a coacting controlling device operatively connected with the valve, said controlling device having its ram-coacting means disposed at one end of the standard to be actuated alternately by the upper and lower elements of the ram.

10. In alifting jack, the combination of a standard, a lifting ram guided in the standard, a lifting screw coacting with said ram, an air-operated motor geared to the lifting screw, a valve for establishing and cutting off flow of operating air to said motor, manual means for operating said valve to start the motor in either direction and to stop it, and means for automatically shifting said valve to stop position when the ram reaches both upper and lower predetermined limits of motion, said means comprising recessed shoulders on the upper and the lower portions of the ram, and a coacting controlling deviceoperatively connected with the valve, said controlling device having its ram-coaoting means disposed at one end of the standard tobe actuated alternately by theupper and lower shoulders of the ram.

, 11. In a lifting jack, the combination of astandard, a lifting ram guided in the standard, a lifting screw (reacting with said ram, an air-operated motor'geared to the lifting screw, a valve for establishing and cutting off flow of operating air to said motor, manual means for operating said valve to start the motor in either direction and to stop it, and means for automatically shifting said valve to stop position when the ram reaches both upper and lower predetermined limits of mo-. tion, said means comprising elements'on the upper and the lower portions of the ram, and a coacting controlling device operatively connected with the valve, said controlling device being mounted for movement in opposite directions in a vertical plane and having its ram-coacting means disposed at one end of the standard to be actuated alternately by thrustofthe upper and lower elements of the ram.

12. In a lifting jack, the combination of a standard, a lifting. ram guided in the stand ard, a lifting screw coacting with said ram, an air-operated motor geared to the lifting screw, a valve for establishing and cutting off flow of operating air to said motor, manual means for operating said valve to start the motor in either direction and to stop it, and means for automatically shifting said valve to stop position when the ram reaches a predetermined limit of motion, said means comprising an element recessed in the ram, a controlling device having a dog to cooperate with said recessed element, and an operative connection between said dog and said valve.

13. In a lifting jack, the combination of a standard, a lifting r m guided in the standard, a lifting screw coacting with said ram, an air-operated motor geared to the lifting screw, a valve for establishing and cutting oil flow of operating air to said motor, manual means for operating said valve to start the motor in either direction and to stop it, and means for automatically shifting said valve to stop position when the ram reaches both upper and lower predetermined limits of motion, said means comprising elements recessed in the upper and lower portions of the ram, and a coacting controlling device operatively connected with the valve, said controlling device having its ram-coacting I means disposed at one end of the standard to be actuated alternately by the upper and lower elements of the ram.

In witness whereof, I hereunto subscribe my name.

JOHN W'. HOBBS. 

